Feed water regulation



Jan. 9, 1934. D. K. swAR'rwouT, JR

FEED WATER REGULATION Filed March 25, 1931 ZSheets-Sheet l OE/vro/y K, JWAETM/our J6.

Jan. 9, 1934. D. K. SWARTWOUT, JR

FEED WATER REGULATION Filed March 25. 1931 2 Sheets-Sheet 2 gwvento'v Dan 70w JrvAerz vour. J2.

Patented Jan. 9, 1934 UNITED STATES.

FEED WATER REGULATION Denton K. Swartwout, Jr., Cleveland, Ohio, as-

signor to The Swartwout Company, Cleveland, Ohio, a corporation of Ohio Application March 25, 1931. Serial No. 525,153

9 Claims.

This invention relates to feed water regulation, and has for its principal object to provide a method and apparatus whereby the flow of feed water to a steam boiler or the like may be accurately controlled.

' More specifically the invention relates to a hook up whereby the differential pressure at the feed water valve is utilized in such manner as to more accurately control the variation in pressure ahead of and across this valve than has heretofore been possible with known types of regulators.

In the present hook-up an excess pressure valve is placed in the feed water line in advance 1 of the feed water valve, and the operating pressure to this excess pressure valve is under the influence of a differential pressure valve connected across the feed water valve. The excess pressure valve may also be placed under the control of a pressure generator or the like which responds to variations in boiler water level or other boiler conditions, the generator pressure being transmitted to the excess pressure valve preferably through the medium of a pilot valve whichis connected in the operating pressure line between the differential control valve and excess pressure valve.

The present invention is particularly adapted for use in connection with high pressure boilers where a more accurate control of the differential pressure across the feed water valve than is possible with hook-ups such as shown in the patent to R. W. Andrews No. 1,396,239. With such hookups, the excess pressure is perniciously influenced 35 more or less by the building-up action of the valve spring of the excess pressure valve, that is, as the flow of water to the boiler decreases, the higher will be the excess carried in the spring and the greater will be the differential pressure across the feed water valve. Obviously, if the differential pressure across the feed water valve is maintained substantially constant, the variation'in water level at the boiler will be enormous- 1y less than it would be if this differential were permitted to vary.

With the present form of regulator hook-up the differential pressure across the feed water valve is maintained substantially constant regardless of the rate of flow of water through the feed conduit. The constancy of pressure drop across the'feed valve is assured by using the pressure differential at that point to actuate a highly sensitive mechanism in which any building up action in springs or the like is negligible throughout the range of its use. This mechanism in'turn 1 controls an excess pressure control valve in the feed water line, but is not appreciably effected by any variation in resistance to movement which the excess pressure control valve may offer under any conditions.

In the drawingsz- Figure 1, illustrates more or less diagrammatically a boiler and part of the feed water system therefor, embodying a feed water regulator hook-up which serves to carry out my novel method of control.

Fig. 2, is an enlarged view in sectional elevation of the differential pressure and pilot valves shown in Fig. 1.

The reference numberal 5 conventionally designates a boiler drum containing water and steam which is supplied with water under pressure higher than boiler pressure through a feed line 6. Above the water level in the drum 5, a conduit 7 is connected to the drum, said conduit carrying a pressure generator 8, which may be of any preferred type, the construction of which may be readily understood by referring to Patent No. 1,193,125, issued to N. G. Copley, August 1, 1916. Briefly, the generator consists of an inner tube whichis connected through the conduits 7 and 7a to the steam and water space in the boiler, and a surrounding fluid chamber which connects through a conduit 9 with the diaphragm chamber of a feed water valve 10, and also through a branch conduit 9a with the diaphragm chamber of the pilot valve 11.

The action of the generator is well understood. it being sufficient to state that when the water level in the boiler falls, the amount of steam in the inner tube increases and vaporizes a portion of the fluid in the surrounding chamber of the generator, thus increasing the pressure in said chamber, which pressure is communicated to the diaphragm chambers of the valves 10 and 11. Conversely, if the water level in the boiler rises, pressure in the generator chamber drops and likewise the pressure in the valve diaphragm chambers is reduced.

An excess pressure control valve 12 is connected in the feed line 6 in advance of the valve 10 and with my novel arrangement, this valve may be placed in the line'near or remote from the valve 10. This valve is preferably of that type which is opened by a spring and closed by pressure upon its diaphragm, the diaphragm chamber of the valve being connected up with a source of operating pressure through a line or conduit 13. It is well understood that due to variation in pump pressure, and'also due to the opening and closing movements of the valve 10 in response to changes in boiler conditions, the pressure in the conduit 6 on each side of the valve 10 has a tendency to vary, causing a surging action in the line, and it is the purpose of this invention to utilize the differential pressure across the feed water valve 10 in such manner as to maintain this differential pressure substantially constant.

The difierential pressure in the line 6 measured across the feed water valve 10 is transmitted to the diaphragm of a master control valve 14 through conduits 15 and 16, and the valve 14 is connected into the operating pressure line 13.

The valve 14 is provided with a relatively sensitive diaphragm which acts to move a valve member 14a. When this valve member is depressed, it acts to throttle the port 14?) leading to atmosphere and at the same time increase the operating pressure through the line 13 and in the diaphragm chamber of the valve 12. The valve member 14a is depressed against the resistance of a spring 140 adjustable by nut 14d. It is also preferred to provide this valve with an adjustable lower seat 14c such as disclosed in the copending application of H. J. Mastenbrook, Serial No. 451,560, so that the effective travel of the valve closure member relatively to said seat may be adjusted as desired. When the closure member 14a of the valve 14 moves upwardly, as here shown, atmospheric pressure is tended to be established in the line 13 through port or conduit 14b and the operating pressure in said line drops and likewise pressure in the diaphragm chamber 12a of valve 12 lowers and the closure member of valve 12 moves toward open position, permitting an increase in pressure ahead of the feed valve 10. Conversely, when the closure member 14a of valve 14 moves downwardly towards its seat, atmospheric pressure is throttled off from the line 13 and the operating pressure builds up in the line 13 and chamber 12a, exerting pressure on the diaphragm of the valve 12 and moving the closure member of said valve toward closed position, and hence lowering the pressure ahead of the feed valve 10.

Any variation in differential pressure in the conduit 6 across the feed, water valve 10 is instantly transmitted to the diaphragm of the valve 14 and the latter acts, through the line 13, to adjust the operating pressure for the excess pressure valve 12 in accordance with the departure from the desired differential. Any small change in diiferential pressure across the feed valve causes a relatively great change in pressure in the line 13, which instantly acts on the valve 12 to whatever extent is necessary to re-establish the desired differential pressure. Thus any variation in differential pressure is instantly rectified and the differential pressure maintained constant regardless of the amount of water flowing through the feed conduit. The flow of water between the valve 12 and the boiler will be almost exactly in proportion to the demands of the boiler regardless of variation in pump pressure ahead of the valve 12. This smooth feed of water also protects the economizer, indicated at 17, which is shown as positioned between the valve 12 and the boiler.

The pilot valve 11 may serve as an emergency valve and is placed in the line 13, said valve being provided with a diaphragm chamber 11a, connecting with the conduit 9a, and a diaphragm which acts to depress a valve member 11b against the resistance of an adjustable spring 110. This valve may also have an adjustable lower seat 11d substantially similar to valve 14 in which a port lle is formed and connects with the inlet side of the line 13. This port is normally open. A port or connection 111 leading to atmosphere is provided, and when a predetermined pressure is exerted on the valve diaphragm, the valve member 111) moves downwardly and throttles the port lle and admits atmosphere into the line 13. This valve may be adjusted so that if there is an unusual drop in water level, the line 13 will be opened to the atmosphere and the valve 12 will be fully opened, so that a maximum flow of feed water is permitted in the line 6 in accordance with pump pressure, in which event the differential valve 14 will cease to control the valve 12 until the water level builds up above the abnormally low level whereupon the spring lifts the closure member of the valve 11 to close communication with atmosphere and open the line 13.

The differential pressure lines 15 and 16 are provided with hand valves 18 and 19 and are connected by a by-pass line 20 provided with a valve 20a. This serves as a means for protecting the diaphragm of the difierential valve 14. If there is pressure in the boiler with the feed pumps idle, valves 19 and 20a should be open and valve 18 closed, while if the pumps are running and there is no boiler pressure, valves 18 and 200. should be open and the valve 19 closed. When the boiler is started, valves 18 and 19 should be closed and 20a opened. When pressure builds up in the boiler 5 and feed line 6, either valve 18 or 19 should be gradually opened to al low the difierential pressure to equalize on both sides of the valve diaphragm.

While the foregoing describes a preferred form of my invention illustrated in a specific layout, and while for example, I have shown the excess pressure control valve positioned ahead of the feed water regulating valve, it will be understood that this order maybe reversed all within the precepts of my invention. Other changes and modifications should occur to those skilled in the art without departing from the spirit of my invention and I do not care to be limited to this specific showing or in any manner other than by the claims appended hereto.

I claim:

1. In a boiler feed water system, the method of controlling the difierential pressure across a feed water valve which consists in utilizing the differential pressure to control a separate operating pressure which in turn is used to effect control of the excess pressure in advance of said valve.

2. In a boiler feed water system, the method of controlling the differential pressure across a feed water valve, which consists in controlling an excess pressure valve in the feed line in advance of the feed water valve, and supplying a separate operating pressure to said excess pressure valve when the differential pressure across the feed water valve departs from a predetermined differ-- ential pressure.

3. In a boiler feed water system, a feed water conduit, a regulating valve in said conduit, an excess pressure valve in said conduit and means for utilizing the differential pressure measured across the regulating valve to control a separate operating pressure for said excess pressure valve in accordance with the variations of the differential pressure relative to a predetermined value.

4. In a boiler feed water system, a feed water conduit, a feed water valve in said conduit and an excess pressure regulating valve in advance of said feed valve, a conduit leading from a source of fluid pressure to said excess pressure valve and adapted to transmit operating pressure thereto, and means for utilizing the differential pressure across the feed valve for controlling the operating pressure of the said excess pressure regulating valve in accordance with the variations of the differential pressure relative to a predetermined value.

5. In a boiler feed Water system, a feed water conduit, a feed water valve in said conduit, an excess pressure valve in said conduit in advance of said feed valve, a conduit for transmitting operating pressure to said excess pressure valve, a difierential pressure valve in said last-named conduit, and means for transmitting the difierential pressure across the feed valve to the operating pressure conduit to thereby vary the operating pressure on the excess pressure valve in accordance with the departure of the difierential pressure from a predetermined value.

6. In a boiler feed water system, a feed water conduit, a regulating valve in said conduit, an excess pressure valve in said conduit in advance of said regulating valve, a conduit for transmitting operating pressure to said excess pressure valve, a differential pressure valve in said last named conduit and means for transmitting the differential pressure at the regulating valve to the differential pressure valve to control the operating pressure to the excess pressure valve, and a thermal controlled valve in said operating pressure conduit.

'7. In a boiler feed water system, a feed water pipe, a feed water regulating valve in said pipe controlled according to variations in a boiler condition, an excess pressure valve also in said pipe, a conduit for transmitting operating pressure to said excess pressure valve, a difierential pressure valve responsive to variations in pressure drop across the feed water regulating valve and a pilot valve in said conduit, said pilot valve being controlled in accordance with variations in boiler conditions.

8. A boiler feed water system having a feed water conduit, a regulating valve in said conduit, means actuable by changes of water level in the boiler for operating the regulating valve, an excess pressure valve in said conduit ahead of the regulating valve, first means responsive to variations in pressure drop across the regulating valve for operating the excess pressure valve, and second means responsive to boiler water level for operating the excess pressure valve.

9. A boiler feed water system having a feed water conduit, a regulating valve in said conduit, means actuable by changes of water level in the boiler for operating the regulating valve, an excess pressure valve in said conduit ahead of the regulating valve, first means responsive to variations in pressure drop across the regulating valve for operating the excess pressure valve, and second means responsive to boiler water level for operating the excess pressure valve, the second means arranged to render the first means ineffective to operate the excess pressure valve when the latter is actuated by the second means.

DENTON K. SWAR'I'WOUT, JR. 

